Natural gas as an energy source is well suited to mitigate global climate change and a good transition step on the road towards the use of low-carbon sources of energy. In a recent paper published in the journal "Geochemistry, Geophysics and Geosystems", L. M. Cathles concludes that "substitution of natural gas [for coal and some oil] reduces global warming by 40% of that which could be attained by the substitution of zero carbon energy sources."

Natural gas burns much "cleaner" than coal and oil, but gas leakage during production and transportation might counteract the greenhouse gas emission benefits of natural gas as an energy source. For this reason gas leakage rates, especially from unconventional gas wells, are discussed in the article. Based on recent data on gas leakage during completion of shale gas or tight sand wells provided by the industry to the U.S. Environmental Protection Agency (EPA), the author states that "leakage is ~0.01% [of production] and similar to that from conventional gas well completions and workovers". This leakage rate is much lower than previously published data suggest and benefits from the fact that 93.5% of the 1578 unconventional gas wells in the study "were green completed ‐ that is they were connected to a pipeline in the pre‐initial production stage so there was no need for them to be either vented or flared." These data show that green completions indeed have the potential to reduce gas leakage of unconventional wells significantly. Green completion are compulsory in the U.S. from 2015 onwards.